Shaft Mounted Electromagnetic Clutch, Type SL SL series power-on clutches are used to couple two parallel shafts. The armature hub assembly is mounted to the same shaft as the rotor assembly. The armature hub accommodates a pulley, gear, sprocket, etc., to transmit torque to the second shaft. The field assembly is mounted on the shaft and retained by a loose fitting pin or bracket through the anti-rotation tab.